Portable drug delivery devices are used for the administration of a medicinal fluid or drug that is suitable for the self-administration by a patient. A drug injection device is especially useful in the shape of a pen, which can be handled easily and kept everywhere available. A type of drug delivery device is constructed to be refillable and reusable many times. A dose of a drug is delivered by means of a drive mechanism, which also allows to set the dose that is to be dispensed.
U.S. Pat. No. 5,827,232 discloses a medication delivery pen comprising a reusable pen body and a disposable cartridge assembly including a plunger. The cartridge assembly can be disassembled from the pen body after the medication therein has been exhausted, and the used cartridge assembly may be replaced.
It is an object of the present invention to disclose a new drive assembly for a drug delivery device and a new drug delivery device.